can't get the frontmatter inform via the string source, but can get the frontmatter when read from the 'mdx' files

[BertramYe]

Describe the bug

failed to get the fontmatter via the code here below with the latest version : [email protected] and also set the parseFrontmatter: true

import { compileMDX } from 'next-mdx-remote/rsc'

const BlogDetailPage = async() => {
    const source = `
        ---
            title: Bertram's Blogs
            author: Bertram
        ---
    
        # Welcome to my MDX page!
    
        This is some **bold** and _italics_ text.
        
        This is a list in markdown:
        - One
        - Two
        - Three
    `
   const {frontmatter,content }  = await compileMDX<{ title: string,author:string }>({
        source:source,
        options: { parseFrontmatter: true },
    })
    console.log('frontmatter',frontmatter) // the frontmatter result is {}
    return (
        <div>
            {content}
        </div>
    )
}
export default BlogDetailPage

but when I put the source in to a mdx files and then I read from the mdx files with the same codes like below here, I can get the frontmatter correctly

import { compileMDX } from 'next-mdx-remote/rsc'
import fs from 'fs'
import path from 'path'


const BlogDetailPage = async() => {
     const data = fs.readFileSync(path.join(process.cwd(),'mdxfiles/test.mdx')) // test.mdx has the same code of the `souce` above 
   const {frontmatter,content }  = await compileMDX<{ title: string,author:string }>({
        source:source,
        options: { parseFrontmatter: true },
    })
    console.log('frontmatter',frontmatter) // the frontmatter result is : frontmatter: { title: "Bertram's Blogs", author: 'Bertram' })
    return (
        <div>
            {content}
        </div>
    )
}
export default BlogDetailPage

Reproduction

you can try on you self side

next-mdx-remote version

v 5.0.0 and also I have tried with the version next-mdx-remote@canary the result is the same

[talatkuyuk]

You are doing wrong in indentations. Remove all indentations from the string of source.

const BlogDetailPage = async() => {
    const source = `
---
title: Bertram's Blogs
author: Bertram
---
    
# Welcome to my MDX page!
    
This is some **bold** and _italics_ text.
        
This is a list in markdown:
- One
- Two
- Three
`
    // ...
}